Gas turbines for power generation systems must satisfy the highest demands with respect to reliability, power, efficiency, economy, and operating service life. Modern high-efficiency combustion turbines have firing temperatures that exceed about 2,300° F. (1,260° C.), and firing temperatures continue to increase as demand for more efficient engines continues. Many components that form the combustor and “hot gas path” turbine sections are directly exposed to aggressive hot combustion gases. The use of coatings on turbine components such as combustors, combustion liners, combustion transition pieces, combustion hardware, blades (buckets), vanes (nozzles) and shrouds is important in commercial gas turbine engines.
Superalloy, such as GTD 111 and its serial alloys, have been largely used in gas turbine industry due to their excellent mechanical properties, oxidization resistance and corrosion resistance. They, however, have poor weldability due to a tendency for liquation cracking and strain age cracking (SAC). Due to the poor weldability of GTD 111 and its serial alloys, weld filler materials have been usually selected to sacrifice mechanical properties to meet weldability requirements.